<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>02_外间距测试</title>
    <style>
        body {
            margin: 0;
        }
        * {
            margin: 0;
            padding: 0;
        }
        .fu{
            background-color: rgba(255,255,0,0.3);
            overflow:hidden;
        }
        .fu>div{
            width:100px;
            height:100px;
            background-color: rgba(0,0,255,.6);
            border:2px solid #00f;
            color:#fff;
            font-size:25px;
            font-weight:bold;
        }
        .z1 {
            margin-bottom: 30px;
            margin-top:50px;
        }
        .z2{
            margin-top: 50px;
        }
        .z4{
            margin-bottom:50px;
        }
        .z3{
            margin:10px;

            margin: 0 auto;
        }
        span{
            border: 2px solid #f00;
        }
        .s2{
            margin: 30px;
        }

    </style>
</head>
<body>
<span>span1</span><span class="s2">span2</span><span>span3</span>
<div class="fu">
    <div class="z1">子元素1</div>
    <div class="z2">子元素2</div>
    <div class="z3">子元素3</div>
    <div class="z4">子元素4</div>
</div>
</body>
</html>